Latch for piston rods



M. A. GARRISON 1 Sept. 14, 1954 LATCH FOR PISTON RODS 2 Sheets-Sheet 1 Filed Nov. 24, 1950 INVENTOR.

prraeusr s P 14, 1954 M. A. GARRISON 2,688,952

LATCH FOR PISTON RODS Filed Nov. 24, 1950 2 Sheets-Sheet 2 .3 Q F q /Q a q 3 0 51 r" 1 a 3 g 3 H g, ,mg, Q 01%;? m N N v r d Ln e e d c m d fi 6 i O I m vs 6 1 N i 5 Ii;

I I l I l I i I Mae/a 7. 6922/80, 9 INVENTOR.

Patented Sept. 14, 1954 LATCH FOR PISTON RODS Marion A.- Garrison,

South Pasadena, Calif.,'as signor to Kay-Brunner Steel Products, Inc,

Los Angeles, Calif., a corporation of Delaware Application November 24, 1950, Serial No. 197,341

This invention relates to power operated earth moving equipment and is particularly directed to a novel form of latch construction for relieving a piston rod of a gravity load imposed by an earth-engaging tool While the tool is held in an inoperative raised position.

Gravity actuated earth-engaging tools are commonly employed on earth moving equipment. Such tools are lowered into operative position by gravity and are raised to an inoperative po sition by means of hydraulic cylinder assemblies. Unless some form of mechanical latch is provided for securing the tool in its inoperative raised position the weight of the tool imposes a back pressure on the hydraulic fluid supplied to the piston of the hydraulic cylinder assembly. The seal rings on the piston are therefore required to be continuously active in order that the pressure of the hydraulic fluid shall maintain the ground-engaging tool in its inoperative raised position.

In accordance with my invention I provide an automatic latch which acts to hold the groundengaging tool in its inoperative raised position without imposing any back pressure on the hydraulic system and without requiring the hydraulic system to maintain the tool in elevated position. The construction of the latch is such that it is automatically released when pressure is applied to move the piston in a direction to lower the tool.

I have chosen to illustrate my invention as applied to a self-powered mobile loader device, but this environment is by way of illustration only, and it is to be understood that the automatic latch device is useful with apparatus of other types.

A feature of my invention is that the latch may be constructed so that the piston rod is latched against movement in either one of its directions of movement.

Other features and objects and advantages of this invention will appearhereinafter.

In the drawings:

Figure 1 is a perspective view partly broken away showing a mobile loader device having a gravity actuated scarifier, and showing a preferred embodiment of my invention interposed between the hydraulic cylinder assembly and the scarifier tool.

Figure 2 is a side elevation partly broken away and partly in section showing details of a preferred form of my invention in connection with the power cylinder assembly.

Figure 3 is a view similar to Figure 2 showing 8 Claims. (Cl. 121-40) the position of the parts shortly after the initial extending movement of the piston rod.

Figure 4 is an end elevation partly broken away of the device shown in Figure 3.

Figure 5 shows a modified form of my invention for automatically latching the piston rod in its extended position.

Referring to the drawings, the power cylinder assembly generally designated It may be mounted on a mobile device having a ground-engaging gravity actuated tool l2 pivotally mounted on one end thereof. Pivot pins [3 may be provided for connecting the parallel arms IA of the tool'to the frame of the mobile device As shown in the drawings the ground-engaging tool l2 takes the form of a scarifier having a weighted bar l5 extending transversely of the vehicle I I and having a plurality of downwardly extending teeth l6 spaced thereon at intervals. A lug |1 may be welded or otherwise secured to one of the arms I4. A pair of straps |8 form a continuation of the lug I1 and are secured thereto by welding. The free ends of the straps are separated to form a yoke l9.

As shown in Figure 2, the yoke I9 is pivotally connected by means of pin 20 to the forwardly projecting ear 2| provided on the sleeve 22. The ear 2| is joined to the sleeve 22 by means of welding 23. The sleeve 22 is provided with a central axially extending bore 24 which is terminated at one end by the ear 2| and which is terminated at the other end by the annular shoulder 25. A smaller bore 26 extends axially through the one end of the sleeve 22 and communicates with the bore 24.

The power cylinder assembly l0 includes a cylindrical shell 21 positioned between spaced heads 28 and 29. The shell 2! and heads 28 and 29 are maintained in assembled relationship by means of the tie rods 30. The piston 3| is mounted to reciprocate within the shell 21, and

this piston is secured to the piston rod 32 by any convenient means such as, for example, by the threaded nut 33. The piston rod 32 extends axially of the shell 21 and projects through the head 21 and through the stuffing box gland 34. The projecting end of the piston rod 32 is slidably received within the sleeve bore 26. An enlargement 35 may be formed integrally on the projecting end of the piston rod or may be formed as a separate ring welded or otherwise secured in place. This enlargement is received within the sleeve bore 24. One side of the enlargement 35 is provided with a radial shoulder 36 adapted to engage the shoulder 25. The other side of mitted through the parts l1,

the enlargement is tapered to provide a frustoconical surface 31.

A plurality of latching pins 38 are provided for releasably securing the sleeve 22 with respect to the stationary body 39. :is fixed with respect to the cylindrical shell 21 r and may conveniently be carried on extensions of The body 39 38 radially inwardly. Cover plates 43 serve, to

close the open ends of the radial bores 4 land also to engage the outer end of the compression springs 42. The cover plates 43 are secured in position by means of suitable attachment elements 44, which are threaded into the body 39.

The inner ends 45 of the latching pins 38 are bevelled for engagement with the frusto-conical surface 31 on the enlargement 35. A cylindrical portion 46 on these latching pins each extends through an aperture 41 provided on the sleeve 22. When the latching pins 38 project through the apertures 4'! the sleeve 22 is effectively latched 1 against movement with respect to the stationary body 39. When the latching pins 38 are retracted (as described below) against the action of the springs 42 the sleeve 22 is free to travel with the piston rod 32.

In the operation of that form of my invention shown in Figures 1-4, the latching pins 33 are normally in position asshown in Figure 2 so that the sleeve 22 is maintained in latching position. The

ground-engaging scarifier tool 12 is thus latched in its inoperative raised position, as shown in Figure 1 since the weight of the tool is transl8, 20 and 2! to the sleeve 22. When the operator desires to lower the scarifier I2 he actuates a valve (not shown) which applies hydraulic pressure through the fitting 48 to cause the piston 3| to move to the right as shown in Figure 2. The tapered surface 3? on the piston enlargement 35 then acts on the bevelled surfaces 45 of the latching pins 38 to cause them to move radially outwardly against the action of the springs 42. As soon as the cylindrical portion 46 of the pins 38 is retracted out of the apertures 41 the weight of the scarifier l2 acting about the pivots l3 applies a force to the ears 2i and sleeve 22, causing the sleeve to move to the right. The action ofgravity in lowering the scarifier 12 may be supplemented by continuing to apply hydraulic pressure through the fitting 48. In this case the extreme forward end 50 of the piston rod 32 engages the radial surface 5! on the ear 2| so that a positive force is applied to move the ear 2i toward the right as viewed in Figure 2.

When it is desired to retract the scarifier 12 to its inoperative raised position, the operator actuates the control valve (not shown) to apply hydraulic pressure through the fitting 52. This applies hydraulic pressure on the right side of. the piston 31 as viewed in Figure 2 and causes it to move to the left. This brings shoulders 36 and 25 into contact and brings the sleeve 22;

into the central opening 53' within the body 39. The sleeve 22 is provided with a bevelled portion 54 which engages theb'evelled ends 45 on the latching pins 38 and retracts them against the action of the compression springs 42. tinued movement of the piston 32 toward the Con-j 4 left as viewed in Figure 2 brings the latching pins 38into alignment with the apertures 41 provided in the sleeve 22. The springs 42 then move the latching pins ,38 into latching position as shown in Figure 2.

It is recognized that instead of hydraulic pressure the power cylinder assembly 10 may be operated by air pressure or by vacuum pressure. The power. cylinder assembly 10 is pivotally mounted on the frame of-the vehicle I l by means of a pivot pin 59 so that the entire assembly may oscillate through a small angle about this pin when the piston rod is extended and retracted. In the modified form of my invention shown in Figure ,5 the sleeve is latched in its fully extended position instead of in its fully retracted position. In Figure 5 the body 390. is carried on the tie rod extensions 3% and held in place by means of nuts 46a in a manner similar to that described above. However, the extensions 30a are considerably longer than the tie rod extensions 363 by the amount of the stroke of the piston rod 32a. The piston rod 32av is provided with an enlargementtfia. This enlargement has a frusto-conical surface 37a. which is engaged by the bevelled ends '45a on the. latching pins 38a. The sleeve 22d extends through a central opening in the body 39d and carries the lug 21a which is connected by means of the 'pin 26a to the yoke l'9a.. -Whenthe piston rod 32a is fully extended as shown in Figure 5'Ythe compression springs 42a move the latching pins 38a into the apertures 41a. provided in the sleeve 22a. The sleeve 22a is thus latched against movement with respect to the stationary body 39a.

When the piston rod 32;; is retracted toward the left as viewed in Figure 5 the'frusto-con'ical surface am engages the bevelled ends 45a of the latching ins 38a andthereby moves the latching pins radially outwardly against the action of the compression springs 42a. 'When the cylindrical'portion of the latching pins haspassed out of the ,aperturesAla the sleeve22a is free to move to the left asviewed in Figure 5. 'The force of the pressure fluid admitted through fitting 52 moves the piston rod 32a to the left, and this force may be applied to bring the shoulder 50a on the enlargement t5aagainst the surface 5la on the plate BEL This plate 50 is bored for slidingreception of the iston rod 32a and is secured'to the sleeve 22 by means of welding 6!.

When the piston 32a is caused to move to the right byfpressure fiuid'the endjsurfa'ce 36a on the enlargement 35a engages the end surface 25a on the sleeve 22a to moveit'to the right. When the slanting surface 54a on the sleeve 22a engages the bevelled surface 45a on the latching pins 380., the pins are moved radially outward against the action of the springs42a. When the apertures' 41a register with the pins 38a the latter connecting the heads to' prevent disassembly of the headsand shell, the tie rods 'each'having ex tending portions at oneend, a" body secured to the extending portions of the tie rods. adjacent one of the heads, the body having a central opening, a sleeve mounted for movement within the opening, a piston rod, a piston on the rod reciprocable within the shell, an enlargement on the piston rod at the extending end thereof, the sleeve having a central bore to receive the enlargement in telescopic relation, the sleeve having an aperture communicating with said bore, a latching element movably mounted on the body extending into said aperture to latch the sleeve against relative axial movement with respect to said body, and cooperating parts on the enlargement and latching element whereby axial movement of the enlargement within the sleeve bore away from said heads serves to move the latching element out of said aperture.

2. A releasable latch for a power cylinder assembly comprising in combination: a cylindrical shell, heads at opposite ends of the shell, tie rods connecting the heads to prevent disassembly of the heads and shell, the tie rods each having extending portions at one end, a body secured to the extending portions of the tie rods remote from both of said heads, the body having a central opening, a sleeve mounted for movement 4 within the opening, a piston rod, a piston on the rod reciprocable within the shell, an enlargement on the piston rod at the extending end thereof, the sleeve having a central bore to receive the enlargement in telescopic relation, the sleeve having an aperture communicating with said bore, a latching element movably mounted on the body extending into said aperture to latch the sleeve against relative axial movement with respect to said body, and cooperating parts on the enlargement and latching element whereby axial movement of the enlargement within the sleeve bore toward said heads serves to move the latching element out of said aperture.

3. A releasable latch for a power cylinder assembly, comprising in combination: a cylindrical shell, heads at opposite ends of said shell, mounting rods extending from one end of said shell, a body secured to said mounting rods and axially adjustable thereon, the body having a central opening coaxial with said cylindrical shell, a sleeve mounted for movement within the opening, a piston rod, a piston on the rod reciprocable within the shell, an enlargement on the piston rod at the extended end thereof, the sleeve having a central bore to receive the enlargement in telescopic relation, the sleeve having an aperture communicating with said bore, a latching element movably mounted on the body extending into said aperture to latch the sleeve against relative axial movement with respect to said body, and cooperating parts on the enlargement and latching element whereby axial movement of the enlargement within the sleeve bore in one direction serves to move the latching element out of said aperture.

4. A releasable latch for a power cylinder assembly, comprising in combination: a cylindrical shell, heads at opposite ends of said shell, mounting rods extending from one end of said shell, a body secured to said mounting rods and axially adjustable thereon, the body having a central opening in coaxial relation with said cylindrical shell, a movable sleeve adapted to be secured within the central opening in the body, the sleeve having a central bore, a piston for said shell, a piston rod extending therefrom and having an enlargement at its extended end, the enlargement being secured within said bore of the sleeve, cooperating parts on the enlargement and sleeve permitting limited relative axial movement between the piston rod and the sleeve, the sleeve having an aperture communicating with said bore, a latching pin radially slidable on the body extending into said aperture to latch the sleeve against relative axial movement with respect to said body, a spring acting to move the latching p-in into the aperture, and cooperating parts on the enlargement and latching pin whereby axial movement of the enlargement within the sleeve bore serves to move the latching pin out of said aperture against the action of the spring.

5. A combination as set forth in claim 3, wherein: said body is mounted adjacent said shell and said piston rod is latched when in its retracted position relative to said shell.

6. A combination as set forth in claim 3, wherein: said body is mounted in spaced relation to said shell and said piston rod is latched when in its extended position relative to said shell.

'7. A combination as set forth in claim 4, wherein: said body is mounted adjacent said shell and said iston rod is latched when in its retracted portion relative to said shell.

8. A combination as set forth in claim 4, wherein: said body is mounted in spaced relation to said shell and said piston rod is latched when in its extended position relative to said shell.

References Cited in the file of this patent UNITED STATES PATENTS Number Name Date 1,845,176 Palm n Feb. 16, 1932 1,852,453 Forman Apr. 5, 1932 1,975,147 I-Iartdorn Oct. 2, 1934 2,074,772 Brown Mar. 23, 1937 2,274,668 Crawford et al Mar. 3, 1942 2,303,320 Benjamin et al. Dec. 1, 1942 FOREIGN PATENTS Number Country Date 234,500 Switzerland Jan. 16, 1945 

